Black-cab rapist John Worboys could be freed within weeks after the Government opted not to challenge his release.

Justice Secretary David Gauke decided it would not be appropriate to seek a judicial review of the case after taking legal advice.

Despite the decision, lawyers for victims confirmed they intend to move ahead with their own challenge next week.

An outcry erupted earlier this month after the Parole Board directed the release of Worboys, 60, after a decade behind bars.

He was jailed indefinitely in 2009, with a minimum term of eight years, for drugging and sexually assaulting women passengers.

Worboys was convicted of 19 offences against 12 victims but has been linked to more than 100 complaints in total.

Last weekend it emerged Mr Gauke had commissioned advice on the possibility of taking the highly unusual step of seeking a judicial review.

If the Government had been successful in a court challenge, Worboys could have been kept behind bars while the case was reconsidered.

In a statement to the Commons on Friday, Mr Gauke said he could not give details of the legal advice he was given but noted that the bar for a judicial review to succeed is “very high”.

He said: “I have made clear that I will not bring a legal challenge to the Parole Board’s decision unless there is a reasonable prospect of success.

“Having taken on considered and expert legal advice, I have decided it would not be appropriate for me as Secretary of State to proceed with such a case.

“I understand that some will be disappointed in my decision, but I have acted swiftly to ensure this issue is examined and, hopefully, provide some clarity for victims.”

The case could still be reviewed in the courts after it emerged earlier this week that lawyers for two women were planning to launch their own legal challenge.

Following the Government’s announcement, their solicitor Harriet Wistrich said: “We can confirm that in the absence of any unexpected and compelling response from the Parole Board to our pre-action correspondence, we intend to launch judicial review proceedings against the Parole Board next week.

“The decision by the Secretary of State does not weaken our case at this stage.”

Mayor of London Sadiq Khan also said he had instructed counsel over the possibility of a judicial review of the decision.

Mr Khan said: “I am deeply concerned and unhappy about the prospect of John Worboys’s impending release.”

Mr Gauke emphasised that Worboys will not be released until his licence conditions have been finalised, and victims signed up to a contact scheme have had their say on the restrictions.

He also disclosed that a review announced last week will be widened to look at whether there should be a mechanism to allow parole decisions to be reconsidered.

He said: “The Worboys case has made clear to me that there are some aspects of the Parole Board’s decision-making process which need to be examined and improved.”

Anger over the episode intensified amid complaints victims were not kept informed over the case or the licence conditions that will be placed on Worboys.

Mr Gauke said the Chief Inspector of Probation has been asked to conduct a “fact-finding exercise” to confirm whether processes relating to victims were adequately followed by the National Probation Service in the case.

The Parole Board said it noted the Government’s decision not to proceed with judicial review proceedings, and welcomed the expansion of the review.

Worboys was convicted of one count of rape, five sexual assaults, one attempted sexual assault, and 12 of administering a substance with intent.